Is Body Mass Human Capital in Sumo? Outcome of Globalization and Formation of Human Capital in Japan
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Munich Personal RePEc Archive Is body mass human capital in sumo? Outcome of globalization and formation of human capital in Japan Yamamura, Eiji 5 October 2013 Online at https://mpra.ub.uni-muenchen.de/50866/ MPRA Paper No. 50866, posted 22 Oct 2013 06:48 UTC Is body mass human capital in sumo? Outcome of globalization and formation of human capital in Japan Eiji Yamamura *Corresponding author. Department of Economics, Seinan Gakuin University, 6-2-92 Nishijin, Sawara-ku, Fukuoka 814-8511, Japan. E-mail address: [email protected] Tel: +81 92 823 4543; Fax: +81 92 823 2506 1 ABSTRACT Sumo wrestling is a traditional fighting sport in Japan and has been popular since the 18th century (the Edo period). Using a data set for all sumo wrestlers in the post-World War II period, this paper investigates how wrestlers’ body mass index (BMI) is associated with their win rate and absence rate. Further, the effect of BMI is compared between an early period (before the emergence of foreign wrestlers) and later period (after the emergence of foreign wrestlers). After accounting for endogenous bias using instrumental variables, the key findings are that (1) there is no positive relationship between the BMI and win rate in either the early or later period and (2) there is a positive relationship between the BMI and absence rate in the later period but not in the early period. From the findings in this paper, I make the argument that an increase in the number of immigrants with human capital different from that of domestic labor leads the domestic labor to obtain human capital that does not match its characteristics, thereby reducing the performance of domestic labor. JEL classification: L83; J24; N35; I15; Keywords: Sumo wrestling, Body mass index, Human capital, International labor mobility; Immigrant Running Title: Globalization of sumo 2 Introduction Sumo wrestling is a traditional fighting sport in Japan and has been popular since the 18th century. Following World War II, sumo, like other professional sports, such as football (Berlinschi et al., 2013) and baseball (Schmidt and Berri, 2005), has become globalized. In 1968, Takamiyama became the first non-Asian to reach the top division (makuuchi)1 in sumo. Twenty-five years later, in 1993, Akebono became the first foreign-born yokozuna (the highest rank in the top division). Both Takamiyama and Akebono were born in the United States. Since the retirement of Takanohana in 2003, there has been no domestic Japanese yokozuna. In 2012, 7.5% of sumo wrestlers were officially listed as foreigners, and 33% of wrestlers in the top division were foreigners2. Following these drastic changes, sumo has become an international sport in the 21st century. Differences in the labor quality of sumo wrestlers might be due to technical skill and physical strength. Sumo does not have weight categories, and hence, an increase in body mass might result in higher performance. Hence, the body mass might be considered as human capital in the sumo labor market3. Furthermore, foreign wrestlers, especially those born in the United States, have a great advantage in terms of body mass. “Upon their initiation into the sumo world, foreign wrestlers are already equipped with a physique equivalent to that of wrestlers in the top division. They have trained in American football or basketball, and have been excellent players” (Nakajima 2003, 62). In other words, these foreign wrestlers were not obese even though their body mass was extremely high. As a consequence, competitive pressure increased, giving domestic sumo wrestlers a great incentive to increase body mass.4 On the other hand, extra weight seems to increase injury, which hampers the wrestler’s performance. 1 There are six divisions in sumo: makuuchi (maximum of 42 wrestlers), jūryō (fixed at 28 wrestlers), makushita (fixed at 120 wrestlers), sandanme (fixed at 200 wrestlers), jonidan (approximately 230 wrestlers), and jonokuchi (approximately 80 wrestlers). In total, there are approximately 730 wrestlers attending each tournament. Wrestlers enter sumo in the lowest division, jonokuchi, and ability permitting, work their way up to the top division. 2 In response to the increasing numbers of foreign wrestlers, in 1992, the Japan Sumo Association began regulating the inflow of foreign wrestlers (Nakajima 2003, 120). 3 To put it more precisely, through traditional training, the type of physique required for sumo wrestling can be considered as human capital specific to sumo (Nakajima, 2003, 63–66). However, owing to the limited data and difficulty of measuring physique, this paper uses the body mass index. 4 It was pointed out that there have been rigged sumo matches (Duggan and Levitt 2002). This inevitably impedes fair and open competition. However, most matches have not been rigged, resulting in competitive pressure. 3 This is the negative effect of body mass. Wrestlers are thought to train to obtain an optimum body mass that trades off these positive and negative effects. However, in 2000, the average body fat ratio was 38.4%, which is far higher than ideal for an athlete (Nakajima 2003, 59)5. “The upper weight limit of a Japanese wrestler with consideration of muscular strength was estimated to be 180 kg. That is, it is not appropriate from the viewpoint of exercise that a wrestler’s weight exceeds 180 kg” (Nakajima 2003, 60). However, after the emergence of Takamiyama, there have been 18 wrestlers weighing in excess of 180 kg. The inflow of foreign wrestlers has led Japanese wrestlers to misestimate the optimum body mass. Previous works on sumo (Duggan and Levitt 2002; West 2004) have focused on the norm or the rule shared in the closed sumo world. However, the sumo world has been under the influence of globalization and thus affected by an inflow of foreign-born labor. It is worth investigating the effect of the increasing number of foreign wrestlers on human capital accumulation of domestic wrestlers to explore the impact of immigrants in the labor market. Many works have investigated an individual’s physical characteristics (or sporting activities) and their outcomes in the labor market (e.g., Ewing 1998; Barron et al., 2000; Persico et al., 2004: Lechner, 2009; Rooth 2009; 2011; Böckerman et al., 2010). However, these works did not take international labor mobility into account. The sumo world is generally characterized as having been closed to strangers and so was not influenced from the outside until after World War II. That is, Japanese wrestlers are thought to have shared and behaved according to a social norm. On the other hand, the critical influence of international labor mobility has been observed in other professional sports (Schmidt and Berri, 2005; Berlinschi et al., 2013). Naturally, the question arises whether globalization affects the behavior of sumo wrestlers. Analyzing the sumo labor market can be regarded as a natural experiment for examining how inflow of heterogeneous labor affects a closed traditional labor market governed by a social norm. To explore the question, using the tournament records of sumo wrestlers in the post-World War II period (1945–2013), during which there was a drastic change in the sumo labor market, this paper considers how the body mass index (BMI) is associated with the win rate and absence rate of sumo wrestlers. It also compares the relationships before and after the emergence of foreign wrestlers. The paper is organized as follows. Section 2 explains the data set and simple econometric framework. The results of the estimations and a discussion are provided in 5 The ideal body fat ratio is 10% and 13% for a soccer player and American football player, respectively. 4 Section 3. The final section offers concluding observations. Data and methods In this paper, I use the win rate and absence rate to capture the performance of wrestlers. An increase in body mass is expected to improve wrestlers’ performance because a wrestler with a better physique will have an advantage. The degree of fatness cannot appropriately be captured by an individual’s weight. This is because the taller someone is, the heavier they will be for the same degree of fatness. The BMI is calculated from a person's weight and height, and is a reliable indicator of body fatness for adults6. In the field of economics, the BMI is generally used to capture the degree of fatness (e.g., Zellner et al., 2004; 2007; Chrzanowska et al, 2007; Vignerova et al., 2007; Saint Onge et al., 2008; Yamamura 2012). Although a higher BMI can benefit a sumo wrestler, it also increases the probability of injury, thus lowering performance. Hence, it is an empirical question whether body mass is positively associated with a wrestler’s performance. This paper addresses this question. 2.1. Data There are six Grand Sumo Tournaments (basho) each year. In each tournament, there are 15 bouts. This paper mainly uses wrestlers’ tournament-level data7. Table 1 presents construction of the data used for this paper. Data 1 consists of tournament records of the top division for each wrestler. Within the top division, there are roughly five ranks: Yokozuna (the highest rank), Ozaki (the second rank), Sekiwake (the third rank), Komusubi (the fourth rank) and Maegashira (the fifth rank). To put it more 6 BMI = weight (kg) / (height (m))2. The BMI is not necessarily a suitable proxy variable for obesity in the sumo world because the average body fat ratio of sumo wrestlers in the top division is around 20–25%. Gaining weight does not always mean obesity. What is more important is the balance between the upper and the lower half of the body. However, data on this balance are not available and so cannot be used for statistical analysis.